A 4&1/2 year old girl born to consangious(2 degree) parents presented with, seizures( staring look & unresponsiveness) at the age of 2 years, was put on gardinal (but seizures recurred shifted to eptoin 3 months back.). 6 months later (at the age of 2&1/2 years), child started having episodes of vomiting nonbilious & non projectile,15-20 per dayl. each episode lasting for 10-12 days , for every 3-4 months ,initially later every 1-2 months. ass with loss of appetite and weight. development normal. h/o death of elder sister at the age of 3 years with c/o vomiting, &suspected liver disease (reports n a) o/e----poorly built and nourished vitals--- hr 110 / min. bp 124/90 (hypertension) rr 26/min. hepatomegaly (mild) no spleen. othes systems normal. investigations.----- cbp--- hb 10 tlc-- 5600/cumm plt -- adequate. rft---normal. abg--- normal.uppar gi endoscopy --- mild esophagitis.barium meal f/t normal, montoux -- negative. usg abd --- mild hepatomegaly. csf --normal. ct---normal. sr ammonia, pyruvate -- normal. lactate--- elevated(twice upper limit) urinary vma and urinary protoporphyrinogen negative. please suggest further investigations,dd and management.